Tampon, especially for feminine hygiene, and a process and apparatus for producing this

ABSTRACT

A process for forming a tampon having a relatively high density, compressed core and a plurality of lower density longitudinal ribs is disclosed. The longitudinal ribs have a softer fiber structure and a coarser capillary structure and extend radially from the core. The process includes forming a fibrous tampon blank, radially pressing a circumferential surface of the blank over spaced apart longitudinally extending portions to form spaced apart ribs, exposing the longitudinal ribs to a radially applied second pressure to form a tampon having a relatively high density, compressed core and a plurality of lower density longitudinal ribs extending therefrom. The longitudinal ribs are separated one from another by outwardly open longitudinal grooves, at least where they extend from the core, and they form a soft, essentially smoothly cylindrical outer surface of the tampon.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of prior application Ser.No. 08/427,468, filed Apr. 24, 1995, now U.S. Pat. No. 6,310,269, whichis a continuation of application Ser. No. 08/124,374 filed Sep. 20, 1993now abandoned, which is a continuation of application Ser. No.07/929,844 now abandoned filed Aug. 13, 1992, which is continuationapplication Ser. No. 07/799,922 now abandoned, filed Nov. 26, 1991,which is a continuation application of Ser. No. 07/596,454, filed Oct.12, 1990 now abandoned, which are hereby incorporated by reference andall abandoned.

BACKGROUND OF THE INVENTION

The invention relates to a tampon, especially for feminine hygiene,having a relatively high density compressed core and a plurality oflower density/longitudinal ribs, as well as, to a process and anapparatus for producing the tampon.

A tampon of the abovementioned generic type is known from GermanAuslegeschrift 1,491,161. This tampon has proved appropriate in practicebecause of its high absorption capacity, fluid retention capacity, rateof absorption, stability and buckling strength. For this, the tampon haslongitudinal grooves which are caused by pointed press jaws and on eachof the two sides of which occur longitudinal ribs which are pressed tothe approximately cylindrical final form of the tampon during asubsequent pressing operation by means of press jaws with partiallycylindrical press faces.

SUMMARY OF THE INVENTION

The object on which the invention is based is to improve the tampon ofthe abovementioned generic type in such a way that the absorptioncapacity and rate of absorption of the tampon appertaining to the twoare essentially maintained, but the specific absorption capacity of thetampon is increased.

This and other objects are achieved by the tampon disclosed that makesit possible to obtain an appreciable increase in the specific absorptioncapacity (ml/g), whilst preserving the hitherto obtained absorptioncapacity and rate of absorption, with a surprisingly smaller amount offibre material being used. This effect is attributable to a coarsercapillary structure of the fibre material in the outer layer of thetampon.

Thus, it was found that a tampon according to the invention consistingof 100% rayon fibres with a weight of 2.4 g without the withdrawalstring can have a specific absorption capacity of 4.8 ml/g with a rateof absorption of 1.9 ml/s. The absorption capacity of such a tampon at astatic counterpressure of 20 mbars is 11.3 ml. In a test with apulsating counterpressure of 20 to 110 mbars approximating extremelyclosely to the practical conditions of use, the absorption capacity ofthe tampon according to the invention can amount to 8.0 ml and thespecific absorption capacity to 3.4 ml/g.

The diameter of the tampon is set at between 13 and 15 mm according tothe customary physiological conditions, and the central fibre core canpreferably have a diameter of 4 to 8 mm. A high buckling strength of thetampon can thus be achieved, whilst at the same time the soft surface ofthe tampon guarantees a pleasant handling of the tampon.

The invention relates, furthermore, to a process for producing thistampon. A process of this type is known from German Auslegeschrift1,491,161 already mentioned.

According to the invention, this process for producing the tamponaccording to the invention is improved by means of pressing only narrowstrip-shaped portions of the surface of the blank.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below by means of thediagrammatic drawing of an exemplary embodiment of a tampon and of anapparatus for producing this. In the drawing:

FIG. 1 shows the tampon according to the invention in a middlelongitudinal section along the sectional line I—I in FIG. 2,

FIG. 2 shows a cross-section alone sectional line II—II shown in FIG. 1,showing the tampon of the current invention having outwardly opengrooves,

FIG. 3 shows a cross-section through the preform along the line III—IIIin FIG. 10,

FIG. 4 shows a cross-section of the tampon of the invention, havingclosed grooves,

FIG. 5 shows a diagrammatic view of a preforming press in the openedstate with a winding blank arranged in it,

FIGS. 6 and 7 show a separate closing movement of the pressing dies,wherein FIG. 6 illustrates a first pressing face of the preforming presswith closed press segments, whilst a second, final press face of thepreforming press is illustrated in FIG. 7 showing the sliding plates inthe closed position, wherein all press dies enclose the preform arrangedin it, and

FIGS. 8 and 9 show an alternative sequence of movements of the pressdies, wherein the press segments and the sliding plates aresimultaneously moved into the closed position; FIG. 8 shows anintermediate phase of the pressing procedure and FIG. 9 the press diescompletely closed with the preform arranged in it, and

FIG. 10 shows a partially sectional side view of the apparatus forproducing the tampon with the preforming press and with the followingforming die.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 and 2 show a tampon 10 for feminine hygiene formed from anapproximately cylindrical blank 11 which is shaped by winding up aportion of length of nonwoven material, needled if appropriate. Thenonwoven can consist of natural or synthetic fibres or of a mixture ofsuch fibres. Natural fibres coming under consideration are preferablythose of cotton. Rayon or other synthetic fibres are also highlysuitable. The circumferential surface of this winding blank is pressedin a way known per se radially relative to the longitudinal mid-axis ofthe winding blank over an even number of at least six, preferably eightportions mutually adjacent in the circumferential direction of thewinding blank 11.

According to the invention, these circumferential portions of thewinding blank 11 are exclusively narrowstrip-shaped portions 12, 13 ofthe circumferential surface 14 of the winding blank 11 which arearranged at equal angular distances from one another and which arepressed to produce a preform 15 in FIGS. 3, 7 and 9. As seen incross-section, the preform 15 consists of a central approximatelycircular fibre core 16 of high compression and stability or bucklingstrength and of longitudinal ribs 17 extending radially outwards fromthe fibre core 16 and of a fibre structure softer than that of the fibrecore and of correspondingly coarser capillary structure (FIG. 3). Thelongitudinal ribs 17 are separated from one another by outwardly openlongitudinal grooves 18. Only the soft longitudinal ribs 17 of thepreform 15 are exposed to a low uniform radial pressure duringmanufacture relative to the longitudinal mid-axis 19 of the preform 15,in such a way that the radially outer ends 20 of the longitudinal ribs17 form a soft essentially smoothly cylindrical surface of smallerdiameter corresponding to the final form of the tampon 10.

It was found that the tampon according to the invention has a stability100% higher than that of the known tampon. It was shown, furthermore,that approximately 10% of the fibres used for the tampon can be saved,without any appreciable impairment, if any, of the absorption capacity.In contrast, the rate of absorption is in the upper range of knowntampons, whilst the specific absorption capacity is increasedappreciably in relation to known tampons.

The following table illustrates a comparative test of the tamponaccording to the invention consisting of a needled nonwoven composed of100% of rayon fibres is from Hoechst AG, and a tampon obtainable in thetrade under the commercial designation “Standard o.b.®”:

TABLE Tampon according “Standard to the invention o.b. ®” Tampon 1.Weight (g)without 2.4 2.7 the [recovery tape] withdrawal string 2.Absorption capacity 11.3 11.5-12.5 3. Specific absorption 4.8 4.2-4.5capacity (ml/g) 4. Rate of absorption 1.9 1.5-2.0 5. Absorption capacity8.0 8.6 6. Specific absorption 3.4 3.1 capacity (ml/g) in ABTS test unit

The absorption capacity values indicated in line 2 of the Table weredetermined in a test unit, in which the tampon is surrounded by anelastic diaphragm which exerts a static counterpressure on the tampon,whilst one end of the tampon is sprinkled with water. This resulted inthe specific fluid absorption capacity in ml/g of fibre material of thetampon evident from line 3 of the Table.

The rate of absorption emerging from line 4 was determined in this testarrangement. The values show that, at a weight of the tampon accordingto the invention reduced by approximately 10%, the absorption capacityof the tampon is not essentially reduced in relation to the knowntampon, the rate of absorption is of the upper limit of that of theknown tampon, and the specific absorption capacity is appreciably higherthan in the known tampon. Since the specific absorption capacity isevidence of a better utilization of the absorbency of the fibre materialper unit weight, it is clear that the tampon according to the inventioncan be produced more cheaply as a result of the lower weight ofmaterial.

Lines 5 and 6 of the Table give values for the absorption capacity andthe specific absorption capacity determined in a test arrangementallowing test conditions such as actually occur when the tampon is beingworn.

The system designated as ABTS, corresponding to Absorptive BehaviourTest System, is computer-assisted and serves for the acquisition andprocessing of measurement data regarding the absorption behaviour ofabsorbent products and for controlling the test cycle.

The test of the tampon is conducted under the following conditionswhich, as mentioned, occur approximately in vivo:

-   -   chemical/physical compositions of the test fluid    -   special arrangement of the product, for example inclination    -   positioning of the product in the measuring cell    -   strength of the flow    -   interruption (start/stop) of the flow    -   pressure variant.

The test cycle is software-controlled automatically and allows adialogue between the operator and system. The measurement data arerequired automatically, their evaluation taking place according tostatistical factors. The test cycle for each random sample can betracked on a video screen by means of a measurement curve and, ifappropriate, printed out automatically. Furthermore, the fluiddistribution in the product is represented qualitatively andquantitatively. Moreover, the leakage behaviour of the tampon can bechecked. By leakage is meant the phenomenon in which [menstruation]menstrual fluid can escape between the body wall and tampon. The feed oftest fluid to the tampon is carried out exclusively without pressure,since the fluid level is at the height of the test tampon. The fluid istherefore sucked up into the tampon solely as a result of the wetting ofthe tampon and the wick effect caused by the capillary forces of thelatter, and by means of the pulsating counterpressure on the tamponwhich is felt in practice.

The values determined with this ABTS test device illustrate, in lines 5and 6 of the Table, that, at the pulsating counterpressure indicated,the absorption capacity of the tampon is only slightly lower than in thereference tampon, but here too the specific absorption capacity of thetampon according to the invention per gram of fibre material isapproximately 10% higher than in the reference tampon.

The diameter of the tampon according to the invention is between 13 and15 mm in its final form. The central fibre core 16 has a diameter ofapproximately 4 to 8 mm.

FIG. 4 shows an enlarged cross-sectional representation of the fibrestructure of the tampon according to the invention. It is possible tosee clearly the central fibre core 16, from which extend outwards eightlongitudinal ribs 17 touching one another at their outer ends 20. Thetampon cross-section shows, moreover, that the loose fibre structurewith its coarser capillary structure of the longitudinal ribs 17 ispreserved, despite the concentric pressure to which these longitudinalribs are exposed during the production of the final form of the tampon.In contrast, the fibre core 16 having a high fibre compressionguarantees a stability or buckling strength which is twice as high asthat of the reference tampon and which is of great importance when thetampon is used as a digital tampon.

The figures illustrate an apparatus according to the invention forproducing the tampon. According to FIGS. 5 to 7, this apparatus consistsof two groups of altogether eight press dies arranged in a planeperpendicular to the press axis 21, the first group of press diesforming press segments 22 and the second is group of press dies formingsliding plates 24. In the closing position shown in FIG. 6, the sideflanks 23 of these four press segments 22 form respectively for each ofthe four press dies of the second group guide surfaces which aredesigned as sliding plates 24. At the same time, the press segments 22and the sliding plates 24 serve, as a preforming press, for pressing thewinding blank 11 to produce the preform 15 in FIG. 7. Exclusively presscutters 27 projecting from the end faces 25 and 26 of the press segments22 and of the sliding plates 24 serve for pressing the blank. It isevident from FIGS. 5 to 7 that the press cutters project from the endfaces 25 and 26 of the press segments 22 and sliding plates 24 at equalangular distances and over the same length. The shape and dimensions ofall the press cutters are identical. The press cutters are thereforealso equipped at their front end with the same pressing faces 28 which,in the exemplary embodiment illustrated, each extend parallel to thepress axis and are curved outwards in the manner of a semi-cylinder.

In the exemplary embodiment, the length and width of the press cutters27 radial relative to the press axis 21 amount to 10 mm and 2 mmrespectively. In the closed state of the preforming press, the pressingfaces 26 of the press cutters 27 assume a clear distance of 2 to 4 mmfrom the press axis 21 (FIG. 10.)

In contrast with FIGS. 6 and 7, FIGS. 8 and 9 show a synchronous closingmovement of the press segments 22 and sliding plates 24 in the radialdirection. FIG. 8 shows an intermediate phase of this closing movementof the press dies, whilst the final closing position of these press diesis shown in FIG. 9. The position of the dies shown in FIG. 9 correspondsto the final dimension of the preform 15. The simultaneous pressingmovement of the press segments 22 and the sliding plates 24 has theadvantage, that the geometrical uniformity of the circumferentialstrip-shaped portions 12 and 13 of the preform 15 will be enhanced. Ifthe tampon is wetted by a fluid the tampon will expand to a morecircular shape than in case of the sequential movement of the press diesas shown in FIGS. 6 and 7.

If appropriate, however, the press faces can also have a mutuallydiffering shape. If appropriate, the sliding plates can also be designeddifferently, for example made angular, arrow-shaped or drop-shaped. Itis essential that they load and press only a narrow circumferentialportion of the blank corresponding approximately to a generatrix.Furthermore, the cycle of movement of the two groups of press dies can,where appropriate, also take place simultaneously or interruptedly inthe preforming and post forming and alternately between these twomovement actions. Thus, it can be important, according to the process ofGerman Auslegeschrift 1,491,161, first to close all the press diessimultaneously only up to the circumference of the blank 11, in order tocentre the blank as exact as possible in relation to the press axis 21,before commencing the actual pressing operation, so as to ensure thatthe central fibre core 16 comes to rest exactly in the middle of thetampon 10. This is desirable to obtain the highest possible bucklingstrength or stability of the tampon, above all when the latter is to beused as a digital tampon.

According to FIG. 10, the preforming press described is followed by astationary conical forming die 29. This forming die 29 is arrangedcoaxially relative to the press axis 21. The entry orifice 30 of theforming die has a diameter of 20 mm which corresponds approximately tothe orifice of the preforming press in the closed state of its pressdies which is shown in FIG. 7. The inner face 31 is narrowed towards thecylindrical exit orifice 32 according to an obtuse-angled circular cone,the exit orifice 32 has a diameter of 13 mm and its cross-sectioncorresponds to the final cross-section of the finished tampon 10.Arranged on the input side of the preforming press is a ram 33 whichserves for introducing the winding blank 11 into the preforming pressand for ejecting the preform 15 through the forming die 29. For thispurpose, the ram 33 is arranged movably to and from coaxially inrelation to the press axis 21. Rams of this type are known in the art,and therefore there is no need to represent the driving elements for theram.

The production of the tampon according to the invention by means of theabove-described apparatus is carried out according to the followingprocess: the essentially cylindrical winding blank 11 is pressed solelyon the narrow strip-shaped portions 12 and 13, arranged at equal angulardistances from one another, of the circumferential surface of thewinding blank, to produce the preform 15 which, as seen incross-section, consists of the central approximately circular fibre core16 of high compression and buckling strength or stability and oflongitudinal ribs 17 of softer fibre structure extending radiallyoutwards from the fibre core 16. At the same time, the longitudinal ribs17 are separated from one another by the outwardly open longitudinalgrooves 18. Thereafter, only the soft longitudinal ribs 17 of thepreform 15 are exposed to a low uniform pressure radial relative to thelongitudinal mid-axis of the preform, until the outer ends of thelongitudinal ribs have produced a soft essentially smoothly cylindricalsurface of smaller diameter corresponding to the final form of thetampon 10. As is mentioned, preferably before the actual pressing, thewinding blank 11 is centred relative to the press axis 21 of thepreforming press as a result of the simultaneous- concentric closing ofthe press segments 22 and sliding plate 24 approximately as far as thecircumference of the winding blank.

After the pressing of the preform, the latter is ejected through theforming die 29 by means of the ram 33 and thereby brought to the finaldimension of the tampon which is determined by the exit orifice 32 ofthe forming die 29.

1. A process for producing a tampon comprising the steps of: (i) windingup a length of tape-shaped nonwoven material to form a blank; (ii)radially pressing a circumferential surface of the blank at a firstpressure over an even number of mutually spaced apart longitudinallyextending portions about the circumferential surface of the blank so asto produce a preform, the even number being at least six, only thelongitudinally extending portions of the circumferential surface of theblank being pressed, whereby the preform has a central approximatelycircular compressed fibre core and a plurality of longitudinal ribsformed between the longitudinally extending pressed portions, each ofthe longitudinal ribs extending radially outwards from the fibre coreand being separated from one another by longitudinal grooves, each ofthe longitudinal ribs having a distal end; and (iii) exposing only thelongitudinal ribs to a radially applied second pressure, the secondpressure being less than the first pressure so as to soften the distalends of the longitudinal ribs.
 2. Process according to claim 1, whereinthe step of radially pressing a circumferential surface of the blankcomprises the step of centering the blank between a plurality of pressdies.
 3. Process according to claim 1, further comprising the step ofmoving the preform between the step of radially pressing acircumferential surface of the blank and the step of exposing thelongitudinal ribs to a radially applied second pressure.
 4. Processaccording to claim 1, wherein the step of exposing the longitudinal ribsto a radially applied second pressure provides longitudinal ribs beingseparated from adjacent ribs at their proximal ends by an amount greaterthan at their distal ends.
 5. A process for producing a tamponcomprising the steps of: (i) forming a fibrous tampon blank; (ii)radially pressing a circumferential surface of the blank at a firstpressure over spaced apart longitudinally extending portions about thecircumferential surface of the blank so as to produce a preform having acentral approximately circular compressed fibre core and a plurality oflongitudinal ribs formed between the longitudinally extending pressedportions, each of the longitudinal ribs extending radially outwards froma proximal end at the fibre core and a distal end opposite thereof, andbeing separated from one another by longitudinal grooves, an inner endof the longitudinal grooves defining an outer diameter of the core; and(iii) exposing the longitudinal ribs to a radially applied secondpressure, the second pressure being less than the first pressure to forma tampon having a core of substantially the same outer diameter as thatof the core of the preform and having a soft, essentially smoothlycylindrical outer surface defining an outer diameter that is greaterthan the outer diameter of the core.
 6. Process according to claim 5,wherein the step of exposing the longitudinal ribs to a radially appliedsecond pressure provides longitudinal ribs having a coarser capillarystructure than that of the core.
 7. Process according to claim 5,wherein the step of exposing the longitudinal ribs to a radially appliedsecond pressure provides longitudinal ribs being separated from adjacentribs at their proximal ends by an amount greater than at their distalends.